Well, there are high chances that nothing harmful can happen to you. The prohormone can either lose potency or it can break in an other compound (good or bad). The best idea is to never take risks with something like that even if you hear a lot of good arguments online. If you can't store properly a prohormone, you better resell it what is last of it or dump it in the trash can. If you have in your hand on a prohormone and you don't if it have been well stored or not, you're better put aside and buy a new prohormone.