The scale is copyrighted but you are free to use it without permission or charge by all professionals (researchers and practitioners) as long as you give credit to the authors of the scale:
Diener, E., Wirtz, D., Tov, W., Kim-Prieto, C., Choi. D., Oishi, S., & Biswas-Diener, R. (2009). New measures of well-being: Flourishing and positive and negative feelings. Social Indicators Research, 39, 247-266.
The SPANE is a 12-item questionnaire includes six items to assess positive feelings and six items to assess negative feelings. For both the positive and negative items, three of the items are general (e.g., positive, negative) and three per subscale are more specific (e.g., joyful, sad).
If you would like to know more about SPANE and its related research, please read the following papers, whose references are below.These papers can be found on the reprint page (at UIUC).
Diener, E., Wirtz, D., Tov, W., Kim-Prieto, C., Choi. D., Oishi, S., & Biswas-Diener, R. (In press). New measures of well-being: Flourishing and positive and negative feelings. Social Indicators Research.
Schimmack, U., Diener, E., & Oishi, S. (2002). Life-satisfaction is a momentary judgment and a stable personality characteristic: The use of chronically accessible and stable sources. Journal of Personality, 70, 345-385.
Schimmack, U. & Reisenzein, R. (2002). Experiencing activation: Energetic arousal and tense arousal are not mixtures of valence and activation. Emotion, 2, 412-417
Schimmack, U., & Grob, A. (2000). Dimensional models of core affect: A quantitative comparison by means of structural equation modeling. European Journal of Personality, 14, 325-345.
Diener, E., & Biswas-Diener, R. (2008) Happiness: unlocking the mysteries of psychological wealth. Malden, MA: Wiley-Blackwell.